Method for effecting partial metal plating

ABSTRACT

By the use of an apparatus comprising a supporting and partitioning base having a plurality of spaced openings each having an inner peripheral end edge of a V-shaped cross section for tightly linearly contacting the circumference of the article to be plated when the latter is inserted in place in said opening, and by establishing electric conduction between the terminal of an electrode and the conductive portion in that region of the article located on the inner side of said supporting and partitioning base and not requiring plating via a conductive powder or particles filled on said inner side of the partitioning base, and by immersing that portion of the article protruding on the outer side of said base in the electrolyte, it is possible to accomplish partial metal plating of this article without any complicated steps required in the prior art and to perform mass production at greatly reduced cost.

United States Patent Fukanuma et al.

[151 3,658,663 [451 Apr. 25, 1972 [54] METHOD FOR EFFECTING PARTIAL METAL PLATING [72] inventors: l-lirotaka Fukanuma, Tokyo; KenJl Fujlta; Kenji Kashlura, both of Saitama, all of Japan [73] Assignee: Japan Electro Plating Company,

Kawaguchi, Saitama, Japan [22] Filed: Jan. 25, 1971 [21] Appl. No.: 109,385 [30] Foreign Application Priority Data Mar. 3, 1970 Japan ..45/18399 [52] U.S. Cl. ..204/15,204/297R [51] Int. Cl. .C23b 5/48, C23b 5/70 [58] Field of Search ..208/15,297

[56] References Cited UNITED STATES PATENTS 148,409 3/1874 Bush ..204/297 R 258,214 5/1882 Brinckman... .....204/297 R 1,970,459 8/1934 Kelly....- ..204/297 R 2,115,403 4/1938 Verschragen.... ..204/16 3,007,855 1 H1961 Ellwood ..204/15 3,043,767 7/1962 Tobey ..204/297 R 3,223,599 12/1965 Taylor ..204/297R 3,271,280 9/1966 Shroff ..204/297 R FOREIGN PATENTS OR APPLICATIONS 423,442 2/1935 Great Britain .l ..204/15 Primary Examiner-John H. Mack Assistant Examiner-T. Tufariello Attorney-Linton & Linton [57] ABSTRACT titioning base and not requiring plating via a conductive powder or particles filled on said inner side of the partitioning base, and by immersing that portion of the article protruding on the outer side of said base in the electrolyte, it is possible to accomplish partial metal plating of this article without any complicated steps required in the prior art and to perform mass production at greatly reduced cost.

1 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the invention The present invention is concerned with a method for effecting partial metal plating, especially electroplating, of articles, and more particularly, it relates to an improved method of accomplishing partial electroplating of articles, especially those having a rounded and non-angled cylindrical circumference with simplified procedure and at much reduced cost.

2. Description of the prior art In the past, it has been the practice to use a specially designed plating apparatus in order to perform partial metal plating of articles, especially in performing electroplating, with gold, of only the base and the inner leads and not the outer leads of transistor headers. In accomplishing this partial electroplating by the use of said'specially designed plating apparatus, it was necessary to render individual articles electroconductive one after another or independently of each other. For this reason, the conventional method had the drawbacks that the plating operation required complicated procedures and that such a method was not suitable for mass production.

SUMMARY OF THE INVENTION lt is, therefore, an object of the present invention to eliminate the drawbacks of the conventional method for effecting partial plating of articles, and to provide an improved method for accomplishing the plating of a large number of articles at greatly reduced cost by establishing electric conduction of articles with a quite simplified procedure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross sectional view of the apparatus which is employed in putting a preferred embodiment of the method of the present invention into practice;

P16. 2 is a perspective view of an example of the supporting and partitioning base of said apparatus; and

FIG. 3 is a perspective view of a transistor header which is an example of the article to be subjected to partial plating.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The method of the present invention will be understood better by referring to the accompanying drawings, especially FIGS. 1 and 2 which show an example of the plating apparatus for use in putting the method of the present invention into practice. In the drawings, like parts are indicated by like reference numerals for the sake of simplicity of explanation. Now, referring to the drawings, reference numeral 1 represents a supporting and partitioning base of a dish-like configuration. This supporting and partitioning base 1 com prises a main plate 1' of a dish-like configuration made of a rubber or plastic material having electro-insulating property and an electro-conductive inner lining metal plate 1'' which lines and covers the inner surfaces of said main plate 1 and which serves as the cathode during the plating operation. The electrically insulated main plate 1 is provided with a number of openings 4, 4, which are formed through the bottom of said main plate 1 in spaced relations relative to each other at predetermined intervals. Each of these openings 4, 4, is intended for insertion therein of the base portion 3 of a transistor header (article to be plated). Each of these openings 4, 4, is of the same V-shaped configuration of the same dimension in its inner peripheral end portion which, when a cylindrical article 2 is inserted in said opening and supported therein, will establish a tight linear contact with the cylindrical circumference of said article. Also, said inner lining metal plate I" is provided with as many apertures 5, 5, as said openings 4, 4 one for each opening 4. The diameter of each aperture 5 is slightly larger than that of the opening 4 intended for supporting the base portion 3 of the transistor header 2. It s ould be understood that said supporting and partitioning base 1 of a dish-like configuration may be substituted by a partitioning base made of a net.

According to the method of the present invention, the steps of plating operation begin with the insertion of the article 2 in one of said openings 4, 4, through the corresponding aperture 5 in such a fashion that that portion of said article 2 requiring partial plating protrudes from the reverse side of said supporting and partitioning base 1. Then, the dish-like supporting and partitioning base 1 is filled, on the inner side thereof, with a powder or particles 6 having good electro-conductivity so that the filler 6 is brought into good contact with the outer leads 7 and the flange 3' of the article 2. Thereafter, the base 3 and the inner leads 8 both of which protrude from the reverse side of the supporting partitioning base 1 are immersed in a metal plating medium liquid or electrolyte by placing this partitioning base 1 on surface of said liquid so as to be set afioaton the liquid which is contained in an electrolyte reservoir 9 to thereby establish electric conduction between an anode made of a conductive metal plate 10 housed within the liquid reservoir 9 and the cathode which, in this example, is composed of the base 3 and the inner leads 8 of the transistor header 2, with the assistance of both the inner lining metal plate I" and the deposited conductive powder or particles 6. At the same time, the partitioning base 1 serves to seal the inner side thereof from the electrolyte. Thus, electroplating may be performed upon connection of the apparatus to a power source.

According to the method of the present invention, the electro-conductive powder or particles fill into any narrow spaces which exist in the external regions of the article 2 to be plated so that this fact contributes to rendering the article 2 highly conductive, thus insuring unfailing plating of only the required portion of the article 2. Also, the method of the present invention completely eliminates the complicated procedure of establishing conduction for each individual article 2 which was required in the prior art; but instead, it allows simultaneouspartial plating of a number of articles very quickly and with great easine'ss, thus markedly increasing the efficiency of the plating operation and reducing the cost. Accordingly, it will be understood by those skilled in the art that the method of the present invention has a further advantage that it can be applied as effectively also to the electroplating of such articles as will require electric conduction at multiple points, which was considered impossible in the prior art.

We claim:

1. An improved method for effecting partial metal plating, especially electroplating, of articles by the use of an apparatus comprising a supporting and partitioning base composed essentially of an electrically insulated dish-like main plate and an electroconductive inner lining metal plate covering the inner surfaces of said base, said base having a plurality of spaced openings formed through the bottom thereof, each opening being of a V-shaped inner peripheral end for tightly linearly fit at the apex of said V-shape to the circumference of the article to be plated when the latter is inserted in place in said opening, said inner lining metal plate having the same number of apertures to correspond to the respective openings of the partitioning base in such a fashion that the diameter of said aperture is slightly greater than that of said opening; and by establishing electric conduction between the conductive portion in that region of the article located on the inner side of said supporting and partitioning base and not requiring plating and the terminal of an electrode located on the outer side of said supporting and partitioning base with the assistance of an electroconductive powder or particles filled on said inner side of the base; and by immersing that region of the article protruding from the outer side of said supporting and partitioning base in a plating medium liquid located on said outer side of said partitioning base. 

